Abstract

A photonic crystal microresonator is proposed in this study that is relocatable in two dimensions. A wavelength-scale resonator with high Q-factor (26,000) and high collection efficiency (80%) is formed and repositioned by simply placing and relocating a curved-microfiber to a new position on the surface of a two-dimensional square lattice photonic crystal slab. The formation of the resonator was confirmed by observing lasing of resonators. Infrared microscope images showed that the lasing site is two-dimensionally relocated in-situ. Spectral tuning was demonstrated by modifying the curvature of the microfiber. Functionalities, such as the two-dimensional relocation, spectral tuning and efficient extraction, which the curved-microfiber coupling offers, may provide an alternative way of coupling with a single quantum dot.

Figures (5)

The formation of waveguide modes in the square lattice photonic crystal slab. Straight-microfiber lies along the Γ-X line of the square lattice. (a) Illustration of the structure. (b) Dispersion of the microfiber-induced waveguide modes (red curve). The inset is the vertical cross section of the Ey pattern at X (kn=0.5). (c) Horizontal cross section of the Hz pattern at X. The Brillouin zone of the square lattice is displayed at the right comer. (d) The cut-off frequencies of the waveguide modes as the microfiber approaches to the PC slab.

(a) Scheme of the 2-D relocatable PC resonator (b) Electric field intensity of the fundamental mode (0th) (c) Spatial profile of the cut-off frequency (left) and the Ey patterns of the 2-D relocatable resonator modes at the slab center (right). Line graphs of the patterns at the fiber contact line (y=0) are overlapped with the profile of the cut-off frequency according to their resonant frequencies (left). Red, orange, and blue lines correspond to 0th, 1st, and 2nd mode, respectively.

(a) Lasing spectrum when the curved-microfiber contacts on the square lattice PC slab (the peak pump power is 2 mW). The L-L curve of the fundamental mode (0th) is shown in the inset. (b) Relocations of the curved-microfiber coupled PC resonators. Localized laser emission spots are detected from various positions in the two-dimensional PC pattern where the microfiber contacts. The images are captured by an infrared camera.

(a) Spectral tuning of the 2-D relocatable resonator with increase of curvature (R) of the curved-microfiber. The lasing wavelength was red-shifted by 8.4 nm from 1497.1 nm to 1505.5 nm (b) Shift of the resonant wavelength of the fundamental mode (0th) predicted by 3-D FDTD computations with increase in R.